Full-bore pipeline check valves adapted for rearrangement into alternative body styles

ABSTRACT

As a representative embodiment of the new and improved fullopening pipeline valve disclosed herein, a tubular valve body is formed of three separable full-bore members adapted to pass pipeline pigs and having a combined axial length corresponding to the standard overall length established by industry for both flanged and weld-end valves of that pipe size and pressure rating. The body members can be alternatively arranged into either of two body styles to enable the full-opening valve to be either welded into a pipeline or bolted into position between a spaced pair of opposed pipeline flanges. The body members include an annular member carrying a pivoted valve disc, with this body member being uniquely adapted to be clamped between a flanged body member and either another flanged body member or a pipeline flange depending upon which body style is required for mounting the full-bore valve in a given pipeline. In either of these body styles, the unique annular body member is wholly confined within the flange bolts so that this body member can be conveniently removed or the pivotally-supported valve disc may be selectively oriented to different angular positions as required to assure the passage of pipeline pigs by simply loosening the flange bolts and rotating the annular body member in relation to the other body members.

United States Patent [191 Wheatley, Jr.

[ 1March 13, 1973 [76] Inventor: Thomas Wheatley, Jr., 8015 Meadowglen,Houston, Tex. 77042 [22] Filed: Nov. 19, 1971 [21] Appl. No.: 200,480

Related US. Application Data [63] Continuation-impart of SerJNo.121,877, March 8, 1971, which is a continuation-impart of Ser. No.23,818, March 30, 1970, abandoned.

[52] US. Cl. ..137/454.2, 137/515.7, 137/268, 15/104.06 [51] Int. Cl..Fl6k 15/03 [58] Field of Search.....l37/5l5.7, 527.8, 268, 454.2,137/515, 515.3, 515.5, 527, 527.2, 527.4; 251/299, 298, 303; 15/104.06

Primary Examiner-Henry T. Klinksiek Assistant Examiner-Robert J. MillerAttorney-Ernest R. Archambeau, Jr. et a1.

[57] ABSTRACT As a representative embodiment of the new and improvedfull-opening pipeline valve disclosed herein, a tubular valve body isformed of three separablefullbore members adapted to pass pipeline pigsand having a combined axial length corresponding to the standard overalllength established by industry for both flanged and weld-end valves ofthat pipe size and pressure rating. The body members can bealternatively arranged into either of two body styles to enable thefull-opening valve to be either welded into a pipeline or bolted intoposition between a spaced pair of opposed pipeline flanges. The bodymembers include an annular member carrying a pivoted valve disc, withthis body member being uniquely adapted to be clamped between a flangedbody member and either another flanged body member or a pipeline flangedepending upon which body style is required for mounting the full-borevalve in a given pipeline. In either of these body styles, the uniqueannular body member is wholly confined within the flange bolts so thatthis body member can be conveniently removed or the pivotally-supportedvalve disc may be selectively oriented to different angular positions asrequired to assure the passage of pipeline pigs by simply loosening theflange bolts and rotating the annular body member in relation to theother body members. 7

17 Claims, 3 Drawing Figures FULL-BORE PIPELINE CHECK VALVES ADAPTED FORREARRANGEMENT INTO ALTERNATIVE BODY STYLES- This application is acontinuation-in-part of application Ser. No. 121,877 filed Mar. 8, 1971,which was a continuation-in-part of application Ser. No. 23,818 filedMar. 30, 1970 (now abandoned).

In the pipeline industry, so-called pipeline pigs are often dispatchedby pressure through a pipeline for either separating fluids passingthrough the pipeline or removing unwanted matter or the like from itsinterior wall. In either case, it will be appreciated that unless thesepigs remain in substantially sealing contact with the pipeline wall, asufficient pressure differential cannot be maintained across the pig toassure its continued passage through the pipeline. Thus, since checkvalves must be installed at spaced intervals in long pipelines, thesecheck valves must be specially designed to allow pipeline pigs to passfreely through the pipeline.

Accordingly, the usual practice heretofore has been to employfull-opening check valves such as those shown in U.S. Pat. Nos.2,969,492 and 3,169,263 which are particularly arranged for passingpipeline pigs. As disclosed in these patents, these swing check valvestypically include a cast or integral tubular valve body having alignedinlet and outlet ports and an upwardly-enlarged central portion which issized to allow a depending pivoted valve disc to swing upwardly abovethe flow passage through the valve body. In this manner, as a pig passesthrough the valve, its forward movement will hopefully swing the pivotedvalve disc away from the valve seat and upwardly into the enlargedcentral portion. Once the pig has passed through the valve, the swingingdisc will return to an intermediate position dictated by the continuedflow of the pipeline fluids.

Although check valves of this naturehave been accepted by the industry,those skilled in the art nevertheless recognize that these valves areinadequate in many respects. For example, the degree of obstruction tothe passage of a pipeline pig which is presented by a valve of thisnature is directly proportional to the weight of its swinging disc andthe angular position of the disc in relation to the vertical. In otherwords, for a given check valve, more force will be required to push apipeline pig through the valve if its swinging disc is pivoted forswinging in a vertical arc than where the disc is pivoted for swingingin an inclined arc. It will be recognized, however, that once one ofthese swing check valves is permanently welded into a pipeline, theangular orientation of its pivoted disc is fixed and no subsequentadjustment can be made without cutting the valve out of the line andrewelding it in another angularly-oriented position. Flanged valves can,of course, be repositioned to change their angular orientation; but thelarger sizes of these valves are, of course, so bulky that such changesare very difficult to make. Thus, from a practical standpoint, typicalswing check valves are rarely, if ever, repositioned to facilitate thepassage of pipeline pigs through them.

Those skilled in the art will also recognize that a conventionalpipeline may alternatively employ either flanged or so-called "weld-endvalves. Thus, heretofore, it has been necessary for manufacturers toprovide both flanged and weld-end valves for each of the many standardsizes and pressure ratings commonly required for pipelines. Suchduplication is obviously expensive if complete inventories are to bemaintained by manufacturers and suppliers of such valves.

Accordingly, it is an object of the present invention to provide new andimproved easily fabricated fullopening check valves which are uniquelyarranged to facilitate either the replacement or the repositioning oftheir pivoted discs without having to remove the valves from a pipeline.

It is a further object of the present invention to provide new andimproved full-opening check valves which are especially designed forpassing pipeline pigs and are adapted to be alternatively arranged forconvenient installation in a pipeline by means of either standardflanges or by welding as dictated by the particular construction of thepipeline These and other objects of the present invention are attainedby providing a selectively-arrangeable fullopening check valve which isadapted to be coupled between opposed end sections of a pipeline and iscomprised of an easily fabricated three-part tubular body including astandard pipe flange having an internal diameter substantially equal tothat of the pipeline, an annular body of uniform thickness having acoaxial valve seat of substantially-equal diameter, and an elongatedtubular member having a flanged enlargeddiameter end portion with anoutside diameter and a bolt circle generally corresponding to those ofthe pipe flange and which is joined by a symmetrically-shaped convergingintermediate portion to a reduced-diameter end portion having aninternal diameter substantially equal to that of the pipeline. Acircular valve disc is pivotally mounted within a coaxial counterboreformed in the downstream face of the annular body and adapted formovement between a closed position in seating engagement with the valveseat and a fully-open position where the valve member is extendedupwardly into the enlarged portion of the tubular member to permit thepassage of pipeline pigs. Where the new and improved check valve is tobe welded into a pipeline, the pipe flange is welded to one of theopposed end sections of the pipeline and the reduced end portion of theelongated tubular member is welded to the other end section of thepipeline. The annular body member is then clamped in sealingrelationship between the pipe flange and the flanged end of the tubularbody member. 0n the other hand, where the check valve of the presentinvention is to be mounted between two spaced flanges in the pipeline,the pipe flange included with the valve body is welded to the reducedend of the tu- I bular body member and bolted to the downstream pipelineflange. The annular body member is then clamped in sealing relationshipbetween the flanged end of the tubular body member and the upstreampipeline flange. V

The novel features of the present invention are set forth withparticularity in the appended claims. The invention, together withfurther objects and advantages thereof, may be best understood by way ofthe following description of exemplary apparatus employing theprinciples of the invention as illustrated in the accompanying drawings,in which:

FIG. 1 is an elevational view in cross-section of a new and improvedfull-opening valve of the present invention when it is arranged to bewelded into a pipeline;

FIG. 2 is a cross-sectional view taken along the lines 2-2 of FIG. 1;and

FIG. 3 shows the new and improved check valve of the present inventionas it will appear when it is arranged for mounting between a pair ofopposed pipeline flanges.

Turning now to FIG. 1, a new and improved fullopening check valvearranged in accordance with the principles of the present invention isdepicted as it will appear when it is to be welded between two opposedend sections 11 and 12 of a typical pipeline through which pipeline pigsare to be passed. As illustrated, the check valve 10 includes a tubularbody shown generally at 13 and having three separable body members whichare joined end-for-end in coincidental alignment by a plurality oftypical stud bolts 14 and nuts 15. The first part of the valve body 13is comprised of a typical commercially-available pipe flange 16 ofstandard dimensions and a pressure rating respectively corresponding toindustry standards established for the pipe size and pressure rating ofthe two pipeline sections 1 1 and 12. Although the particular flange 16illustrated in FIG. 1 is a so-called welding neck flange, it will berecognized that this flange could just as well be either a so-calledslip-on flange or a socket-type flange of an equal pipe size andpressure rating. Thus, as far as the purposes of the present inventionare involved, it is essential only that the flange 16 be a forgedwelding flange of a standard design so that it will be compatible withany standard commercially-available flange of the same pipe size andpressure rating.

The second part of the valve body 13 is an elongated tubular member 17having a specially-designed enlarged-diameter flange 18 on one end whichis joined to a reduced-diameter end portion 19 by asymmetricallyconverging central portion which, for the purposes of theinvention, is a commercially-available concentric reducer weld fitting20 of a suitable size and pressure rating commensurate with the servicerequirements of the valve 10. For the purposes of the present invention,it is essential that the smaller end portion 19 be a short length ofpipe of the same pipe size as the pipeline section 12 and that thesmaller end of the concentric reducer 20 also be of this same pipe size.The pipe size of the larger end of the concentric reducer 20 must, ofcourse, be greater than the pipe size of the pipeline section 11. Thelarger end of the concentric reducer 20 is welded, as at 21, to the rearof the forged flange 18 which, as illustrated in the drawings, isspecially fabricated to have an outside diameter, a thickness and a boltcircle design generally corresponding to the same design parameters ofthe flange 16.

It will be appreciated, therefore, that since the flange 18 should havean outside diameter about the same as the other flange l6 and that theirrespective bolt circle designs must correspond, the larger end of thereducer 20 is limited to a pipe size having an outside diameter which ispreferably about equal or somewhat less than the diameter of the boltcircles of the flanges. Those skilled in the art will, of course,recognize that standard designs of commercially-available forged pipeflanges simply do not meet these requirements. Thus, to best achieve theobjects of the present invention, the flange 18 must be especiallyfabricated. It will be noted, of course, that the flange 18 isfabricated so as to provide sufficient metal strength around the boltholes, as at 22, which is commensurate with the design criteria of theother flange 16. It should be further noted that because of theapproximate correspondence of the bolt circle diameter and the diameterof the larger end of the reducer 20, the bolt holes 22 are drilled onlypartway through the flange 18 and terminated short of the rear face ofthe flange. This, of course, necessitates that the bolt holes 22 bethreaded for threaded engagement with the standard stud bolts, as at 14.It will also be noted in FIG. 1 that the rear face of the fabricatedflange 18 is preferably provided with a boss, as at 23, which isappropriately beveled' to match the larger end of the reducer 20 andprovide sufficient metal reinforcement in the vicinity of the weld 21 toguard against warping of the flange face.

The third part of the valve body 13 is comprised of a thick annularmember 24 having flat, parallel faces 25 and 26 which are appropriatelymachined for sealing engagement with the forward faces of the flange l8and, for example, the flange 16 respectively. As illustrated in FIG. 1the outer diameter of the annular member 24 is selected to permit theannular member to be fully disposed within the confines of the severalstud bolts, as at 14, when they are securing the flanges l6 and 18 toone another. The significance of this selection will be subsequentlyexplained.

To achieve the objects of the present invention, the annular body member24 is cooperatively formed so that its internal bore, as at 27, issubstantially equal to the internal diameter of the flange 16. Twocoaxial counterbores or recesses 28 and 29 are formed in the rear face25 of the annular member 24; and the smaller of these coaxial recessesis cooperatively sized for fully receiving a circular disc-like valvemember 30 which is pivotally mounted on the annular member for swingingbetween its illustrated vertical position and the generally-horizontalposition represented by the dashed lines at 31 in FIG. 1. Asillustrated, the forward face of the pivoted valve member 30 is machinedflat and the perimeter of this face is adapted for seating engagementagainst an annular valve seat 32 provided by the flat,rearwardly-directed shoulder defined between the internal bore 27 andthe smaller coaxial counterbore 28. To provide sealing engagementbetween the valve seat 32 and the forward face of the valve member 30,sealing means are provided such as an O-ring 33 which is disposed in acomplementary coaxial groove formed in the annular body member 24 aroundthe annular valve seat.

As best seen in FIG. 2, the valve member 30 is pivotally coupled to theannular body member 24 by a transversely-oriented pin 34 which istangentially secured across the upper edge of the valve disc androtatably disposed in an elongated recess 35 which is formedhorizontally across the top of the rear face of the enlarged counterbore29 and partially cuts across the top of the smaller counterbore 28. Inthe preferred manner of releasably securing the valve member 30 to theannular body member 24, a pair of restraining straps 36 and 37 areextended across the opposite ends of the elongated recess 35 andsecured, as by screws 38, to the annular member to trap the pin 34 inits recess. As best seen in FIG. 1, the counterbores 28 and 29 are ofsufficient depth to insure that the rear face of the valve disc 30 is atleast flush, if not slightly recessed, within the rear face 25 of theannular body member 24 when the valve disc is seated on the valve seat32.

Where the new and improved full-opening valve of the present inventionis to be installed in a pipeline where spherical pipeline pigs (notshown) are to be employed, it will be appreciated that as one of thesespheres moves between the valve seat 32 and the downstream end piece 19,there will be appreciable annular clearance between the exteriorof thesphere and the interior wall of the reducer 20. Those skilled in the artwill, of course, recognize that if this clearance is quite substantial,there is a distinct risk that the sphere will be slowed to such anextent as it attempts to force the swingingdisc 30 fully open that thesphere will be halted in the reducer 20 instead of progressing on intothe downstream pipeline section 12. Accordingly, to reduce the fluidbypass area around a sphere passing through this portion of the new andimproved valve 10, a suitably-shaped arcuate plate 39 is mounted in anupturned position across the bottom of the internal bores of the flange18 and the reducer 20 and secured there as by a weld 40. It will beappreciated from FIG. 2 that this guide plate 39 will significantlyreduce the amount of fluid bypass area around a sphere passing throughthe valve 10.

Accordingly, with the new and improved full-opening valve 10 assembledas illustrated in FIG. 1 and welded to the two pipeline sections 11 and12, it will be appreciated that the valve will function to pass pipelinefluids from left to right as viewed in the drawing. The actual positionof the swinging disc 30 will, of course, be dependent upon the flowrate, the nature of the pipeline fluids, and the weight and surface areaof the valve disc. Thus, when either a spherical or an elongatedcylindrical pipeline pig (not shown) enters the upstream flange 16, itsleading end will encounter the forward face of the valve disc 30 whileit is at least partially raised off of the valve seat 32. The continuedmovement of the pipeline pig will progressively elevate the swingingvalve disc 30 to the position depicted by the dashed lines 31 so as tocompletely remove the valve disc from the central flow passage throughthe valve body 13. As previously noted, the upturned arcuate guide plate39 will greatly reduce the annular clearance around the pipeline pig tofurther assure that there is a sufficient pressure difierential actingacross the pig to continue to force it on into the downstream pipelinesection 12.

As previously mentioned, the pipeline check valves provided heretoforehave not been suited for selective repositioning of their valve discseven should it be determined that better pipeline pigging operationscould be realized by orienting these valve discs to swing in anon-vertical plane. In keeping with the objects of the presentinvention, therefore, it will be appreciated that the new and improvedcheck valve 10 is uniquely arranged so that the annular body member 24can be selectively positioned to any desired angular position with aminimum of difficulty and without removing the valve from the pipeline.To accomplish this, once the pressure is relieved in the pipeline, theseveral bolt studs 14 are partially loosened and the annular body member24 is rotated in relation to the other body members 16 and 17 until theannular member is in a selected angular position. Once the bolt studs 14are retightened, the valve 10 is, of course, again ready for service.Thus, the new and improved valve 10 can be selectively adjusted toassure that the pivoted disc 30 can be opened with a minimum of force bythe passage of a pipeline pig through the full-bore valve. It will, ofcourse, be appreciated that this unique arrangement of the multi-partbody 13 will also facilitate the removal of the annular body member 24and its associated valve disc 30 for either inspection or replacement.

Turning now to FIG. 3, the new and improved check valve 10 of thepresent invention is illustrated with its several body members 16, 17and 24 rearranged so as to permit the valve to be installed between aspaced pair of opposed pipeline flanges, as at 41 and 42. As depicted,the welding neck flange 16 has been welded, as at 43, to thesmaller-diameter end portion 19 of the tubular body member 17 and theannular body member 24 is disposed between the upstream pipeline flange41 and the specially-fabricated flange 18. The stud bolts 14 areemployed for securing the valve body 13 to the upstream flange 41; andother bolts or studs, as at 44, are employed for bolting the weldingneck flange 16 to the downstream pipeline flange 42. It will, therefore,be appreciated by those skilled in the art that by virtue of this uniquedesign of the check valve 10, the body 13 can be selectively arranged soas to permit it to be alternatively connected into a pipeline: by eitherwelding as depicted in FIG. 1 or by connecting it between opposedpipeline flanges as shown at 41 and 42 in FIG. 3. The operation of thefull-opening valve 10 will, of course, be the same in either instance.

As a further feature of the present invention, it will be appreciatedthat the overall combined length of the three body members 16, 17 and 24is the same regardless of which body style they are to be arranged into.Those skilled in the art will, of course, appreciate that for a givenpipe size and pressure rating, the standard overall lengths of weld-endvalves and flanged valves which have been established by industry areidentical. Thus, by virtue of the unique arrangement of the three bodymembers 16, 17 and 24, their combined length will be equal to thestandard established by industry for valves of a given pipe size andpressure rating. It will be recognized, of course, that the length ofthe small-diameter end member 19 is selected so as to obtain theparticular length required for valves of a given pipe size and pressurerating.

Accordingly, it will be appreciated that the new and improvedfull-opening valves of the present invention are uniquely arranged forassembly as either a flangedend valve or a welding end valve of standardoverall length. By virtue of this, a given valve of the invention can beassembled as dictated by the requirements of a particular pipelineinstallation and will not require stocking of two different body stylesof what would otherwise be identical valves. The savings provided bythis feature are readily apparent. Moreover, by virtue of the uniquedesign of the full-opening check valves of the present invention, thepivoted valve disc can be readily removed or repositioned withoutremoving the other parts of the valve body from the pipeline.l-lereagain, the advantages of this unique arrangement are readilyapparent.

Of paramount importance to the present invention, it will be recognizedthat by arranging each of the body members to have an internal boresubstantially equal to the internal diameter of the associated pipeline,the full-opening valve will be particularly adapted for pipeline piggingoperations.

While only a particular embodiment of the present invention has beenshown and described, it is apparent that changes and modifications maybe made without departing from this invention in its broader aspects;and, therefore, the aim in the appended claims is to cover all suchchanges and modifications as fall within the true spirit and scope ofthis invention.

What is claimed is:

1. A full-opening check valve adapted for coupling into a pipeline of agiven pipe size and internal diameter through which pipeline pigs are tobe passed and comprising: a tubular first body member including asymmetrical portion diverging uniformly from a downstream end having aninternal diameter substantially equal to said given diameter to anupstream end having a larger internal diameter with an annular flangethereon having a plurality of first bolt holes arranged therein in afirst bolt circle in accordance with industry standards for pipe flangesof said given pipe size; an annular second body member having anexternal diameter less than the diameter of said first bolt circle andadapted for mounting in coincidental alignment with said annular flange,said second body member having an internal diameter substantially equalto said given diameter and a coaxial counterbore in its downstream facedefining a coaxial valve seat; a circular valve disc adapted forreception in said counterbore in seating engagement with said valveseat; means pivotally coupling said valve disc to said second bodymember for pivotal movement between a closed position within saidcounterbore and an open position where said valve disc is extendeddownstream of said valve seat within said upstream end of said firstbody member; an annular flanged third body member adapted to be coupledto one of said ends of said first body member and in coincidentalalignment therewith, said third body member having an internal diametersubstantially equal to said given diameter and a plurality of secondbolt holes arranged therein in a second bolt circle substantiallycorresponding to said first bolt circle; and guide means mounted withinthe lower portion of said upstream end of said first body member andcooperatively arranged for guiding pipeline pigs passing from saidsecond body member into said first body member.

2. The full-opening check valve of claim 1 wherein said symmetricalportion of said first body member includes a concentric welding reducerarranged in accordance with industry standards.

3. The full-opening check valve of claim 1 wherein said third bodymember is a pipe flange of said given pipe size arranged in accordancewith industry standards for welding flanges.

4. The full-opening check valve of claim 1 further including a sectionof pipe of said given pipe size welded to one of said first and thirdbody members and in coincidental alignment therewith, the length of saidpipe section being selected so that the combined length of said bodymembers and said pipe section will equal the overall length of valves ofsaid given pipe size as established by industry standards.

5. The full-opening check valve of claim 4 wherein said one body memberis said first body member and said pipe section is welded to saiddownstream end of said symmetrical portion.

6. The full-opening check valve of claim 1 wherein said third bodymember is a pipe flange of said given pipe size arranged in accordancewith industry standards for welding flanges and is mounted on saiddownstream end of said first body member; and further including weldmeans cooperatively joining said third body member to said downstreamend of said first body member.

7. The full-opening check valve of claim 1 wherein said third bodymember is a pipe flange of said given pipe size arranged in accordancewith industry standards for welding flanges and is mounted on the upstream face of said second body member; and further including aplurality of bolts in said first and second bolt holes securing saidfirst and third body members to one another with said second body memberclamped therebetween.

8. A full-opening check valve adapted for welding into a pipeline of agiven pipe size and internal diameter through which pipeline pigs are tobe passed and comprising: a tubular downstream body member including aconcentric welding reducer arranged in accordance with industrystandards having a downstream end with an internal diametersubstantially equal to said given diameter and a larger-diameter end, anannular flange welded on said larger-diameter end and having a pluralityof first bolt holes arranged therein in a first bolt circle inaccordance with industry standards for pipe flanges of said given pipesize, and guide means mounted within the lower portion of saidlarger-diameter end and cooperatively arranged for guiding pipeline pigsinto said downstream end; a tubular upstream body member including awelding flange of said given pipe size arranged in accordance withindustry standards for welding flanges and having a plurality of secondbolt holes arranged therein in a second bolt circle substantiallycorresponding to said first bolt circle; an annular intermediate bodymember having an external diameter less than the diameter of said boltcircles and mounted between said flanges and in coincidental alignmenttherewith, said intermediate body member having an internal diametersubstantially equal to said given diameter and a coaxial counterbore inits downstream face defining a coaxial valve seat; a circular valve discadapted for reception in said counterbore in seating engagement withsaid valve seat; and means pivotally coupling said valve disc to saidintermediate body member for pivotal movement between a closed positionwithin said counterbore and an open position where said valve disc isextended downstream of said valve seat and over said guide means withinsaid downstream body member.

9. The fullopening check valve of claim 8 further including a pluralityof bolts in said first and second bolt holes securing said flanges'toone another with said intermediate body member clamped therebetween.

10. The full-opening check valve of claim 9 wherein said first boltholes extend only partway into said annular flange from the upstreamface thereof and are threaded for threadingly engaging said bolts.

11. The full-opening check valve of claim 8 further including a sectionof pipe of said given pipe size welded to one of said tubular bodymembers and in coincidental alignment therewith, the length of said pipesection being selected so that the combined length of said body membersand said pipe section will substantially equal the overall length ofweld end valves of said given pipe size as established by industrystandards.

12. The full-opening check valve of claim 11 wherein said one tubularbody member is said downstream member and said pipe section is welded tosaid downstream end of said concentric welding reducer.

13. The full-opening check valve of claim 8 wherein said coupling meansinclude a transverse pivot pin mounted across the top of said valvedisc, and a transverse recess formed in said downstream face of saidintermediate body member receiving said pivot pin and cooperativelydefining a pivot surface for pivotally supporting said pivot pin.

14. A full-opening check valve adapted for mounting between opposedupstream and downstream flanges in a pipeline of a given pipe size andinternal diameter through which pipeline pigs are to be passed andcomprising: a tubular downstream body member including a concentricwelding reducer arranged in accordance with industry standards having adownstream end with an internal diameter substantially equal to saidgiven diameter and a larger-diameter end, an annular flange welded onsaid larger-diameter end and having a plurality of first bolt holesarranged therein in a first bolt circle in accordance with industrystandards for pipe flanges of said given pipe size, a welding flange ofsaid given pipe size arranged in accordance with industry standards forwelding flanges and having a plurality of second bolt holes arrangedtherein in a second bolt circle substantially corresponding to saidfirst bolt circle so that said welding flange can be bolted to adownstream flange in a pipeline, means including weld meanscooperatively joining said welding flange to said downstream end of saidwelding reducer, and guide means mounted within the lower portion ofsaid largerdiameter end of said welding reducer and cooperativelyarranged for guiding pipeline pigs into said downstream end of saidwelding reducer; an annular body member having an external diameter lessthan the diameter of said bolt circles and adapted for mounting betweenan upstream pipeline flange and said annular flange, said annular bodymember having an internal diameter substantially equal to said givendiameter and a coaxial counterbore in its downstream face defining acoaxial valve seat; a circular valve disc adapted for reception in saidcounterbore in seating engagement with said valve seat; and meanspivotally coupling said valve disc to said annular body member forpivotal movement between a closed position within said counterbore andan open position where said valve disc is extended downstream of saidvalve seat and over said guide means within said downstream body member.

15. The full-opening check valve of claim 14 wherein said first boltholes extend only partway into said annular flange from the upstreamface thereof and are threaded for threadingly receiving one end offlange bolts securing said annular flange to an upstream pipelineflange.

16. The full-opening check valve of claim 14 wherein said meanscooperatively tjoining said welding flange further include a section 0pipe of said given pipe size joining said welding flange to saiddownstreamend of said welding reducer, the length of said pipe sectionbeing selected so that the combined length of said body members and saidpipe section will substantially equal the overall length of flanged-endvalves of said given pipe size as established by industry standards.

17. The full-opening check valve of claim 14 wherein said coupling meansinclude a transverse pivot pin mounted across the top of said valvedisc, and a transverse recess formed in said downstream face of saidannular body member receiving said pivot pin and cooperatively defininga pivot surface for pivotally supporting said pivot pin.

1. A full-opening check valve adapted for coupling into a pipeline of agiven pipe size and internal diameter through which pipeline pigs are tobe passed and comprising: a tubular first body member including asymmetrical portion diverging uniformly from a downstream end having aninternal diameter substantially equal to said given diameter to anupstream end having a larger internal diameter with an annular flangethereon having a plurality of first bolt holes arranged therein in afirst bolt circle in accordance with industry standards for pipe flangesof said given pipe size; an annular second body memBer having anexternal diameter less than the diameter of said first bolt circle andadapted for mounting in coincidental alignment with said annular flange,said second body member having an internal diameter substantially equalto said given diameter and a coaxial counterbore in its downstream facedefining a coaxial valve seat; a circular valve disc adapted forreception in said counterbore in seating engagement with said valveseat; means pivotally coupling said valve disc to said second bodymember for pivotal movement between a closed position within saidcounterbore and an open position where said valve disc is extendeddownstream of said valve seat within said upstream end of said firstbody member; an annular flanged third body member adapted to be coupledto one of said ends of said first body member and in coincidentalalignment therewith, said third body member having an internal diametersubstantially equal to said given diameter and a plurality of secondbolt holes arranged therein in a second bolt circle substantiallycorresponding to said first bolt circle; and guide means mounted withinthe lower portion of said upstream end of said first body member andcooperatively arranged for guiding pipeline pigs passing from saidsecond body member into said first body member.
 1. A full-opening checkvalve adapted for coupling into a pipeline of a given pipe size andinternal diameter through which pipeline pigs are to be passed andcomprising: a tubular first body member including a symmetrical portiondiverging uniformly from a downstream end having an internal diametersubstantially equal to said given diameter to an upstream end having alarger internal diameter with an annular flange thereon having aplurality of first bolt holes arranged therein in a first bolt circle inaccordance with industry standards for pipe flanges of said given pipesize; an annular second body memBer having an external diameter lessthan the diameter of said first bolt circle and adapted for mounting incoincidental alignment with said annular flange, said second body memberhaving an internal diameter substantially equal to said given diameterand a coaxial counterbore in its downstream face defining a coaxialvalve seat; a circular valve disc adapted for reception in saidcounterbore in seating engagement with said valve seat; means pivotallycoupling said valve disc to said second body member for pivotal movementbetween a closed position within said counterbore and an open positionwhere said valve disc is extended downstream of said valve seat withinsaid upstream end of said first body member; an annular flanged thirdbody member adapted to be coupled to one of said ends of said first bodymember and in coincidental alignment therewith, said third body memberhaving an internal diameter substantially equal to said given diameterand a plurality of second bolt holes arranged therein in a second boltcircle substantially corresponding to said first bolt circle; and guidemeans mounted within the lower portion of said upstream end of saidfirst body member and cooperatively arranged for guiding pipeline pigspassing from said second body member into said first body member.
 2. Thefull-opening check valve of claim 1 wherein said symmetrical portion ofsaid first body member includes a concentric welding reducer arranged inaccordance with industry standards.
 3. The full-opening check valve ofclaim 1 wherein said third body member is a pipe flange of said givenpipe size arranged in accordance with industry standards for weldingflanges.
 4. The full-opening check valve of claim 1 further including asection of pipe of said given pipe size welded to one of said first andthird body members and in coincidental alignment therewith, the lengthof said pipe section being selected so that the combined length of saidbody members and said pipe section will equal the overall length ofvalves of said given pipe size as established by industry standards. 5.The full-opening check valve of claim 4 wherein said one body member issaid first body member and said pipe section is welded to saiddownstream end of said symmetrical portion.
 6. The full-opening checkvalve of claim 1 wherein said third body member is a pipe flange of saidgiven pipe size arranged in accordance with industry standards forwelding flanges and is mounted on said downstream end of said first bodymember; and further including weld means cooperatively joining saidthird body member to said downstream end of said first body member. 7.The full-opening check valve of claim 1 wherein said third body memberis a pipe flange of said given pipe size arranged in accordance withindustry standards for welding flanges and is mounted on the upstreamface of said second body member; and further including a plurality ofbolts in said first and second bolt holes securing said first and thirdbody members to one another with said second body member clampedtherebetween.
 8. A full-opening check valve adapted for welding into apipeline of a given pipe size and internal diameter through whichpipeline pigs are to be passed and comprising: a tubular downstream bodymember including a concentric welding reducer arranged in accordancewith industry standards having a downstream end with an internaldiameter substantially equal to said given diameter and alarger-diameter end, an annular flange welded on said larger-diameterend and having a plurality of first bolt holes arranged therein in afirst bolt circle in accordance with industry standards for pipe flangesof said given pipe size, and guide means mounted within the lowerportion of said larger-diameter end and cooperatively arranged forguiding pipeline pigs into said downstream end; a tubular upstream bodymember including a welding flange of said given pipe size arranged inaccordance with industry standards for welding flanges and having apluRality of second bolt holes arranged therein in a second bolt circlesubstantially corresponding to said first bolt circle; an annularintermediate body member having an external diameter less than thediameter of said bolt circles and mounted between said flanges and incoincidental alignment therewith, said intermediate body member havingan internal diameter substantially equal to said given diameter and acoaxial counterbore in its downstream face defining a coaxial valveseat; a circular valve disc adapted for reception in said counterbore inseating engagement with said valve seat; and means pivotally couplingsaid valve disc to said intermediate body member for pivotal movementbetween a closed position within said counterbore and an open positionwhere said valve disc is extended downstream of said valve seat and oversaid guide means within said downstream body member.
 9. The full-openingcheck valve of claim 8 further including a plurality of bolts in saidfirst and second bolt holes securing said flanges to one another withsaid intermediate body member clamped therebetween.
 10. The full-openingcheck valve of claim 9 wherein said first bolt holes extend only partwayinto said annular flange from the upstream face thereof and are threadedfor threadingly engaging said bolts.
 11. The full-opening check valve ofclaim 8 further including a section of pipe of said given pipe sizewelded to one of said tubular body members and in coincidental alignmenttherewith, the length of said pipe section being selected so that thecombined length of said body members and said pipe section willsubstantially equal the overall length of weld-end valves of said givenpipe size as established by industry standards.
 12. The full-openingcheck valve of claim 11 wherein said one tubular body member is saiddownstream member and said pipe section is welded to said downstream endof said concentric welding reducer.
 13. The full-opening check valve ofclaim 8 wherein said coupling means include a transverse pivot pinmounted across the top of said valve disc, and a transverse recessformed in said downstream face of said intermediate body memberreceiving said pivot pin and cooperatively defining a pivot surface forpivotally supporting said pivot pin.
 14. A full-opening check valveadapted for mounting between opposed upstream and downstream flanges ina pipeline of a given pipe size and internal diameter through whichpipeline pigs are to be passed and comprising: a tubular downstream bodymember including a concentric welding reducer arranged in accordancewith industry standards having a downstream end with an internaldiameter substantially equal to said given diameter and alarger-diameter end, an annular flange welded on said larger-diameterend and having a plurality of first bolt holes arranged therein in afirst bolt circle in accordance with industry standards for pipe flangesof said given pipe size, a welding flange of said given pipe sizearranged in accordance with industry standards for welding flanges andhaving a plurality of second bolt holes arranged therein in a secondbolt circle substantially corresponding to said first bolt circle sothat said welding flange can be bolted to a downstream flange in apipeline, means including weld means cooperatively joining said weldingflange to said downstream end of said welding reducer, and guide meansmounted within the lower portion of said larger-diameter end of saidwelding reducer and cooperatively arranged for guiding pipeline pigsinto said downstream end of said welding reducer; an annular body memberhaving an external diameter less than the diameter of said bolt circlesand adapted for mounting between an upstream pipeline flange and saidannular flange, said annular body member having an internal diametersubstantially equal to said given diameter and a coaxial counterbore inits downstream face defining a coaxial valve seat; a circular valve discadapted for reception in said counterbore in seatinG engagement withsaid valve seat; and means pivotally coupling said valve disc to saidannular body member for pivotal movement between a closed positionwithin said counterbore and an open position where said valve disc isextended downstream of said valve seat and over said guide means withinsaid downstream body member.
 15. The full-opening check valve of claim14 wherein said first bolt holes extend only partway into said annularflange from the upstream face thereof and are threaded for threadinglyreceiving one end of flange bolts securing said annular flange to anupstream pipeline flange.
 16. The full-opening check valve of claim 14wherein said means cooperatively joining said welding flange furtherinclude a section of pipe of said given pipe size joining said weldingflange to said downstream end of said welding reducer, the length ofsaid pipe section being selected so that the combined length of saidbody members and said pipe section will substantially equal the overalllength of flanged-end valves of said given pipe size as established byindustry standards.